Elsewhere in the forum, some people mentioned a neat piece of software called CombineZM which can be used to stack multiple images to produce a single image. A neat application for this is to combine a series of macro shots taken at slightly different focusing distances. The idea being to increase the total depth of field, without compromising quality due to diffraction from small apertures.

So far so good, but what makes it really interesting is the possibility of automating the process. As many of you know, Canon's EOS 40D can be remote controlled by a PC, including the focusing adjustment.

You may have also heard of a program called DSLR Remote Pro, which extends the capabilities of this remote process beyond the facilities of Canon's supplied software. Its developer Chris Breeze has now done the sensible thing and written a script where DSLR Remote Pro can automatically capture a series of images at different focusing distances, ready to feed right into CombineZM.

Pretty amazing results from CombineZM. My initial thought was that it could only do its stuff if there were sharp edges or textured surfaces but on reflection if neither condition applies then it doesn't matter which frame from the stack is used in the final result.

It's nice that DSLR Remote Pro is capable of automating the picture taking process with the Canon EOS 40D or Canon EOS-1D Mark III. I am not aware of any camera which can do this independently by activating an appropriate menu setting and I wonder why not? I imagine that the firmware overhead would be small and for those who need to produce photographs with very large depth of field it would be a time saver.

I have been thinking about what this application does. I will be the first to say that I am not to learned in the more technical side of photography. With this application in mind, wont you get the most detail out of a still subject like the flower example with a low iso and the largest aperture? For example, iso 100 and f22. Then to get a good blur, wouldn't it be easier to just blur out the background in post? I am just wondering because I am very interested in getting the best quality pictures I can and if it means taking 30+ shots and stacking them then so be it...I just want to know. thanx

Yeah, just take one image at F/8 of F/11 (that's the optimal aperture for aps-c lenses), and one at your largest aperture. Then composite them together to get the sharpness of F/11 and the background blur of F/5.6

_________________I take pictures so quickly, my highschool was "Continuous High".

I have been thinking about what this application does. I will be the first to say that I am not to learned in the more technical side of photography. With this application in mind, wont you get the most detail out of a still subject like the flower example with a low iso and the largest aperture? For example, iso 100 and f22. Then to get a good blur, wouldn't it be easier to just blur out the background in post? I am just wondering because I am very interested in getting the best quality pictures I can and if it means taking 30+ shots and stacking them then so be it...I just want to know. thanx

The problem with using small apertures (i.e. f/22) is that the quality of the image starts to degrade after a certain aperture, somewhere around f/8 on most lenses. If you can use multiple images, you get a higher quality image than if you simply took one shot at f/22.

Hi Shagrath,
So if im getting this right, in order to achieve the sharpest quality image, I should not shoot past f/8? Does this mean that the best image quality comes from the bigger apertures like f1.8 and that the bokeh effect just happens? If so, would it be best to just shoot at the largest ap of a lens and stack them? I am felling a little lost with this. Thanx though for mentioning that image quality starts to degrade after about f8.

There are two opposing limits working here. In general, lenses work best stopped down, as many (but not all) lens flaws are reduced by doing so. But, working against this is diffraction. This isn't exactly determined by the lens itself, but the sensor. At small apertures this effect blurs the image. For lower density sensors (up to 12MP APS-C) diffraction softening kicks in just after f/8, or just before for higher density sensors.

Between lens flaws and diffraction, there is a sweet spot. As a rough guideline, good lens quality can be obtained stopped down a little, going up to about f/8, although some lenses do well wide open too. And all this only really matters if you need the best quality possible. If you aim for "good enough" then you have much more flexibility.

Ok! I do want only the best, and if possible I will go for better. I suppose to help understand further, how does one go about finding out a lens' "sweet spot"? Taking both limits of the lens and sensor into consideration, what have the least tolerance? Would it be a hasselblad?

Now that I think about it, going back to the idea of, you can give a photographer a crap camera and he will still take stunning pictures, and give an average joe the top of the line and he wont be able to recreate the same shot, what makes a camera so good in the first place? Dont all/most serious-pro cameras do the same thing? I know the sensors change and the camera build like plastic or steel, but why does a 40D cost X and A Mark3 cost so much more? Why is the Mark3 so much better? megapixels aside, at the bootm line, does the Mark3 take better pictures than the 40D and if so, why? By better im not wondering about what has more bells and whistles to the camera, i want to know about the final image quality.

Sorry if im going on a bit of a rant here I just really want to learn what I can.

By better im not wondering about what has more bells and whistles to the camera, i want to know about the final image quality.

No point having the sharpest lens in the world if it can't focus fast enough, right?

While the 40D is a good camera, the 1D mk III is a better camera. It's weather sealed and more rugged so you're able to use it in weather that would make the 40D fail. It's got a better autofocus system so you'll get shots that the 40D will struggle with. The 1D Mk III's shutter is rated at 300,000 actuations while the 40D's shutter is rated at 100,000 shutter actuations. All else being equal, that means that the 1D Mk III will take 3x more photos than the 40D before breaking down. 10 fps vs 6.5 fps is going to be a difference felt by sports and wildlife photographers.

If all you're interested in is taking photos of test charts to determine lens sharpness, or photographing static scenes or peeping at pixels and commenting on "high ISO performance" then the 40D and 1D Mk III will give similar performance. If you're after a camera that will open up more opportunities and give you more keepers, then you'll see the value in the 1D Mk III.

Having said that, the 40D and 50D are very competent cameras. Lots of professional wedding and portraits photographers depend on them.

FINALLY! Thanks pg, I can always count on you to pull me back down when I've floated too far away from practicality. Thank you. Your reply was exactly what i was looking for. A clear distinction on the value of cameras and a solid answer regarding image quality. Now I know. Thanx again.

One thing that pgtips didn't mention is sensor size - and that's a big one. Especially since you were specifically talking about image quality, C40D.

A bigger sensor is going to produce less noise - noticibly so. Especially at high ISO settings.

I recently got a 7D, and it's great - BUT, nothing like a full frame sensor. If you're interested in image quality (as I am), a full frame sensor is the way to go. Personally, I'm waiting for the next successor to the 5D Mark II. (With the 7D sporting 8 shots a second, I think it's safe to say Canon will give no less speed with the next generation of the 5D Mk II.)